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ABRAM A.v 'BRENEMAN, OF BROOKLYN, ANEIV YORK.

PROCESS or COATING IRON AND sneer. wars nosrrssfs OXIDE.

SPECIFICATION forming part of Letters Patent No. 387,046., dated July 31, 1888.

Application filed January 10, 1888. Serial No. 260,363. (No specimens.)

To aZZ whom it may concern:

Be it known that I, ABRAM A. BRENEMAN, a citizen of the United States, residing at Brooklyn, Kings county, State'of New York,'have invented certain new and useful Improvements in the Process of Coating Iron with Rustless' Oxide, of which the following is a full, clear, and exact specification.

Myinvention relates to thetrcatmentof articles of iron for the purpose of rendering them non-corrodible or non-oxidizable and capable of resisting the deteriorating action of the elements and chemical agents towhich they may be subjected in use; and my invention consists in an improved method, substantially as hereinafter more particularly set forth, of producing upon the articles a surface of the magnetic oxide ofiron. V

It is a well-known fact that the magnetic or black oxide of iron (Fc,O,) is not oxidizable under ordinary conditions of exposure, and attempts have been made to make use of this fact in protecting articles of iron and rendering them non-corrodible under the various uses to which they are applied; and the object of my invention is to provide articles of iron with a substantial and uniform coating or surface of the magnetic oxide.

In carrying out my invention I have discovered that it is necessary to first reduce the surface of the articles to be treated to the state of metallic iron, and in doing this I may make use of various and different methods and means as, for instance, it may be done mechanically by removing the oxidized or otherwise corroded surface of the iron by brushing or sandblasts and the like, although I generally prefer to reduce the surface to the metallic state bysubje'cting the articles to the action of a reducing agent, and I preferably make use of a substance containing a hydrocarbon-ms, for instance,'any'ordinary illuininatinggas. In using this reducing agent I find it preferable to inclose the articles to be treated in a retort or niuflie and to bring the articles to a uniform heat, the degree of which will vary somewhat, according to the character of the articles to be treated; but I have generally found it best to heat the articles to about achcrry-red.

-' The next step in the method is to convert the metallic iron into the magnetic oxide, and

7 best and most available agent.

thereof.

in carrying out this step I subject the articles to the action of an oxidizing agent, and I pref-Q erably make use of ordinary air, as this is the derstood, of course, that the articles should be uniformlyheatcd when exposed to this oxidizing agent, and I preferably carry out my methodl by utilizing the same retortor mnlilc connections, whereby the reducing and oxidizing agents maybe readily applied insuccession.

Vhen the reducing action has been prop- 6 cles to the reducing action of the gas, which produces a coating of metallic iron, and then upon admitting the oxidizing agent it has the effect of penetrating below the surface of the material and removing a certain proportion of s the carbon in the iron beneath the coating and to produce a greater thickness of the magnetic oxide than the first operation. This alternate and successive-treatment may be followed until a coating of oxide of the required or desired 3 thickness is produced, and it will be observed thatat each action the surface is first uniformly reduced to the state of metallic iron, and finally converted into a continuous and uniform coat ing of magnetic oxide by the oxidizing agent. 90

In this way the coating of magnetic oxide, instead of being in a series of layers correspond- 1 ing toeach successive operation, is produced as a single homogeneous layer covering every portion of the surface and interlocking with 5 the particles of. the metal upon which it rests.

: While I have th us described what I consider the best method of carrying out my invention, it will be evident to those skilled in the art that the steps may be performed in various 100 It. will be un- 55 .for both of the essential steps of the invention 60 and providing the muffle with the necessary ways without departing from the principles What I claim is 1. The method, substantially as hereinbeforeset forth, of producing a coating of magnetic oxide upon the surfaces of articles of iron for the purpose of rendering said articles noncorrodihle, which consists in subjecting the uniformly-heated articles to the reducing aciion of a hydrocarbon andthen to the oxidizing action of air.

2. The method, substantially as hereinbefore set forth, of producing a coating of magnetic oxide upon the surface of articles of iron for the purpose of rendering said articles nonaaaoes corrodible, which consists in repeatedly subjecting the uniformly-heated articles to the r 5 alternate and successive action of a reducing agent to bring the surface to the state of metallic iron, and of an oxidizing agent to produce the final coating of magnetic oxide.

In testimony whereof I have signed my name 20 to this specification in the presence of two subscribing witnesses.

ABRAM A. BRENEMAN.

Witnesses:

J. S. BARKER, F. L. FREEMAN. 

